Multiple push-button switch



Patent @fiice 2,8l9,356 Patented Jan. 7, 1958 MULTIPLE PUSH-BUTTON SWITCH Philip Hutt, Milford, Conn., assignor to General Electric Company, a corporation of New York Application January 31, 1957, Serial No. 637,414

6 Claims. (Cl. 200-5) The present invention relates to a multiple electrical switch and particularly a push-button switch with a series of manually controlled buttons which may be depressed to control the operation of several circuits operating through the switch.

Multiple push-button switches have been used in great numbers as appliance switches for electric ranges, washing machines, and room air conditioners. The basic patent for such push-button switches is the Andrews Patent No. 2,431,904 which is assigned to the same assignee as is the present invention. Much engineering effort has been spent in recent years in redesigning this switch to lower its cost and improve its operation. The present invention is the result of such work and it has been put into full scale production for use with electric ranges.

The principal object of this invention is to provide a multiple push-button switch with a novel low-cost method of fastening the cover plate to the insulating base.

A further object of this invention is to eliminate a rivet fastening means between the cover plate and base of an electrical switch so that the cover plate is held in place by the switch terminals rather than by rivets.

A further object of this invention is to provide push buttons having push rods with detent springs for holding the rods steady in the outermost position while one of the other buttons is being actuated.

A further object of this invention is to provide a novel mounting means for a detent spring on the push rods of the buttons of a multiple push-button switch.

The present invention has been illustrated as it is applied to a multiple push-button switch with movable sliders, each having a series of cam surfaces that are acted upon by the push buttons. Usually, one button will be depressed at all times. However, when another button is depressed, it will act upon certain cam surfaces of one or more of the sliders to move certain of the sliders to return the down button back to its outermost position, and at the same time act upon certain predetermined rnovable contacts of the switch to either open or close the circuits through the switch. One feature of my invention is to eliminate the unintentional movement of the push buttons in their outermost positions while one of the buttons is being depressed. This is accomplished by providing each push button with a detent spring of generally hairpin shape so that it will cooperate with formations in the switch base to hold the buttons in a steady position. Each push button consists of a push rod of fiat metal stock and a removable cap that is press-fitted over the outer end of the rod. The lowermost end of the push rod is bent into a rounded shape for cooperation with the cam surfaces of the switch sliders. The hairpin shaped detent spring is hung over the outer end of the push rod to be symmetrically arranged with respect to the rod and confined in this position when the cap is fitted over the rod.

The second feature of this invention is a novel means for fastening the cover plate over the open face of the Cir switch base. The fixed contacts of the switch are mounted near the open face of the switch base, and the terminal ends of these contacts protrude outwardly of the base so that they are accessible when the cover plate is fastened over the open face. In the past, such cover plates had been riveted to the base which is an expensive operation and necessarily increases the size of the switch base. My invention is concerned with the method of arranging the terminals of the switch in two rows, and of providing one row of terminals with shoulder means so that an edge of the cover plate may be arranged under such shoulder means and held thereby. The other row of terminals are arranged substantially perpendicular to the open face of the base and the cover plate is provided with suitable openings that will receive the terminals of this second row. Hence, the cover plate is assembled to the open face of the base by sliding one edge of the cover plate under the shoulder means of one row of terminals, and then by dropping the cover plate over the perpendicular terminals so that the openings are aligned with such terminals and the cover plate moved to its final position. Then, by swaging the side edges of the perpendicular terminals, the cover plate is prevented from becoming disengaged from the base.

My invention will be better understood from the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

Figure l is a top plan view of a multiple push-button switch embodying my invention.

Figure 2 is a cross-sectional side elevational view taken on the lines 2-2 of Figure 1.

Figure 3 is a front cross-sectional elevational view taken on the lines 3-3 of Figure 1.

Figure 4 is an isometric view of a switch sub-assembly that includes one of the push rods of the buttons along with a hairpin-shaped detent spring for the rod.

Figure 5 is a plan view of the back cover plate which is used to close the open face of the switch base.

Figure 6 is an isometric View of a portion of the switch housing showing the open face of the switch base and the cover plate slightly displaced from its final assembled position.

Figure 7 is a bottom plan view of the switch of Figure 1 showing the cover plate in its final assembled position.

Referring in detail to the drawing, and in particular to Figure 3, there is shown a recessed base it of molded insulating material with an open back face 11 that is closed by a separate cover plate of thin sheet insulating material. This combination of the base lid and cover 12 forms a hollow switch housing with an elongated space 13, as seen in Figure 2, for accommodating a group of four movable sliders Usually, each slider 14 has a series of notches or cam surfaces 15 which equal in number the total of push buttons 16 included in the switch. The top face 17 of the switch base, which is hereinafter called the front of the switch, is provided with a series of raised openings 18, one for each push button 16 of the switch. Each push button 16 comprises a push rod 19 that extends through the opening l8 and a removable cap 26 that is engaged to depress the button and actuate the movable sliders 14. The lower and innermost end 21 of the push rod 19 is rounded to provide a suitable operator for the cam surfaces 15 of the sliders.

Now, with particular reference to Figures 2-4 of the drawing, attention is directed to the push rod 19 of the button 16 and a hairpin-shaped detent spring 25 that is hung symmetrically over the outermost bifurcated end of the rod 19. First, the purpose of this detent spring is to steady the push button 16 in its outermost position, while one of the other push buttons is being depressed.

amasse Plu' J One shortcoming with previous push-button switches is that when they are mounted in an upright position as shown in Figures 1 and 3 there is a tendency for some of the buttons to drop and then return to their starting position as another button is being depressed to move the sliders. These switches are oftentimes used with pilot lights that are exposed when the buttons are depressed from their outermost positions. The spring 25 has a U- shaped end 2d the legs of which terminate into an outwardly convex spring finger 2? and finally into a hooked latching portion 23.

Each of the raised openings 18 17 of the base is formed as a box-like appendage 29 that includes a pair of opposed projections 30 on opposite sides of the opening 18 for cooperation with the latching portion 23 of the detent spring 25. Hence, to depress any of the push buttons llti it is first necessary to compress the spring fingers 27 so that they will clear the projections 30 of the opening Once, this is done, the rounded end 21 of the push rod it? quickly moves against the cam surfaces 115 of the sliders to make the necessary adjustment and operate the circuit through the switch. In the meantime, the button 16 which had been previously depressed is forced upwardly by the moving sliders, and the detent spring of this upwardly moving button will first be compressed until the latching portions 28 engage with the projections 3d of the switch base. Consequently, there are two spring forces which tend to retard the movement of the push button namely, the detent spring of the downwardly moving button and the detent spring of the upwardly moving button.

Turning now to a consideration of the fastening means for the cover plate 12 at the back of the switch base 10, attention is directed to Figures 2 and 57. First, it should be understood that the lower edge of each slider 14 is provided with camming surfaces 35 of several configurations for cooperation with the movable contacts 36 f the switch, as best seen in Figure 2. Each of the movable contacts 36 is of cantilever construction where its distal end 37 is arranged to make and break contact with the fixed contacts 33. The fixed end 39 of the movable contact 36 is formed at a right angle with respect to the main portion of the movable contact and permanently fastened to a terminal member dil which is of thin flat metal stock and has its upper end 41 supported in the base and staked as at 42 therein. The lower end of the terminal 40 protrudes outwardly of the base and beyond the open face 11 thereof, as is best seen in Figures 2 and 6.

Returning to a consideration of the fixed contacts 38, they are each of one-piece construction with a contacting portion 435, a staked upper end id in the switch base, and a lower terminal end 45 that is disposed in a parallel manner to the bottom face ill of the switch base lltl and slightly below the cover 12. The terminal end 45 of the fixed contact has a threaded opening for receiving the terminal screw 46 so that the line wires of an electrical appliance such as a range may be through-connected from one switch to the next for controlling the several heating units of the range.

Figure 6 of the drawing is an isometric view of the bottom portion of the switch base 10 showing the open back face 11, the cover plate 12, the perpendicular terminals 40 of the movable contacts 36 and the flatwise terminals of the fixed contacts 38. The cover plate 12 is best shown in the detail plan view of Figure as being of generally rectangular shape with a cutaway edge 50 that is to be nearest the terminals 4-5 of the fixed contacts 38. Openings fill are formed adjacent the opposite edge of the plate for receiving the terminal ends iii of the movable contacts. The edge 5t) of the cover plate is held down by shoulder means 52, one at each side of the terminal end 45. Actually, the cover plate 1'2. is tilted at an angle so that the edge 50 will slide under the shoulder means 52 and then the openings 51 will drop in the top or front face 4 i ever the perpendicular terminals ii). Because of the tilted angle of the cover plate as it is being assembled to the base, the openings 51 must be enlarged. First, there is a rectangular shaped slot 53 and a smaller rectangular slot 54 communicating therewith. The smaller slot 54 has dimensions similar to the transverse crosssection of the terminal 4t! while the larger slot 53 is similar in size to the transverse cross-section of the terminal 40 near the plane of the open face 11 of the base 10. The edge 58' of the cover is first slipped under the shoulder means and then the openings 51 are aligned with the terminals it: and as the cover plate is forced downward, it is slipped further under the shoulder means until the cover plate is in its final assembled position. Then the opposite side edges 55 of the terminals 40 are swaged or deformed slightly so that the cover plate may not be removed.

Modifications of this invention Will occur to those skilled in this art, and it is to be understood, therefore, that this invention is not limited to the particular embodiments disclosed but that it is intended to cover all modifications which are within the true spirit and scope of this invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electrical switch comprising an insulating base and a cover plate, the said base having an open face through which a plurality of terminals extend, there being two spaced rows of such terminals, the terminals of one row extending outwardly and away from the open face of the base, the terminals of the other row having shoulder means cooperating with the said cover plate, and a series of openings in the cover plate for receiving the terminals of the first-mentioned row, while an edge of the cover plate is arranged under the said shoulder means of the terminals of the other row, so that the cover plate is fastened on the base by deforming the terminals of the first row.

2. A multiple push-button switch comprising an insulating housing with an open face that is closed by a cover plate, a plurality of terminals extending through the open face, these terminals being arranged in two spaced rows, the first row extending substantially perpendicular to said open face while the terminals of the second row have shoulder means cooperating with the said cover plate, and a plurality of openings in the cover plate for receiving the terminals of the first row, so that one edge of the cover plate may be located under the shoulder means of the second row of terminals, the said cover plate being held in place by the terminals of the first row which are made to extend over the edge of the openings and hold the cover plate assembled to the housing.

3. A multiple push-button switch comprising a housing having a series of openings in one wall receiving the rods of a group of push buttons, and detent spring means mounted on each rod with a spring finger on each side of the rod for engagement with portions of its receiving opening to hold the buttons in their outermost position against accidental displacement, so that when one button is in the depressed position and another button is being forced down the detent springs of both buttons will retard the movement of the buttons as they exchange positions.

4. A multiple push-button switch comprising a recessed r housing having a series of movable sliders which are actuated by the buttons to control the switching of the several circuits through the switch, each button including a detent spring with a spring finger on each side of the button for engagement with an abutment in the switch housing to hold the buttons in their outermost position against accidental displacement, so that when one button is in the depressed position and another button is being forced down the detent springs of both buttons will retard the movement of the buttons as they exchange positions.

5. A detent spring for a push-button switch, said spring being a thin strip of metal formed in a hairpin shape, each arm of the spring having an outwardly convex intermediate portion and an outwardly concave latching portion at its distal end for locking engagement with inwardly facing abutments of the housing of the switch.

6. A multiple push-button switch comprising in combination a recessed housing with a plurality of movable sliders that control the opening and closing of the several circuits through the switch, one wall of the housing having a series of openings, each opening receiving a push rod of one of the buttons of the switch, the push rods engaging carn surfaces on the sliders for shifting the sliders and insuring that only one button will be fully depressed at any one time, each push rod having a bifurcated outer end onto which a button cap is fastened, a hairpin shaped detent spring hung over the bifurcated end of each push rod and held in place by the cap, each arm of the spring having an outwardly convex intermediate portion and an outwardly concave latching portion at its distal end for locking engagement with inwardly facing abutments of each rod-receiving opening to hold the buttons in their outermost position against accidental displacement.

References Cited in the file of this patent UNITED STATES PATENTS 2,652,470 Batcheller Sept. 15, 1953 2,723,317 'Hutt Nov. 8, 1955 FOREIGN PATENTS 161,948 Switzerland Aug. 1, 1933 

